Operators Experience With Flexible Risers

2002 ◽  
Author(s):  
Gudmund Per Olsen ◽  
Ketil Rongved
Keyword(s):  
Failure Modes ◽  
Lifetime Prediction ◽  
Norsk Hydro ◽  
The Future ◽  
Flexible Risers

Norsk Hydro has more than 150 flexible dynamic risers and service lines in operation. Norsk Hydro’s experience with flexible risers started in 1987 when Petrojarl 1 commenced test production at the Oseberg Field. The paper tells the story about Norsk Hydro’s experience through the 15 years of trials with a new and complicated product. This paper will focus on “what went wrong”. This may seem unfair to the product! However, without flexibles we would probably not have seen such successful field developments as the Troll B and C, Njord, Visund and Snorre B. Challenging production and installation schemes have been put forward and fulfilled. However, hopefully this paper can give an insight in failure modes, and so forth give input to enhanced solutions in order to avoid similar situations in the future. This paper gives an overview over the different approaches which have been taken to give a better qualification of the lifetime prediction of the risers. Some of the specific projects will be presented in detail in other papers on this conference.

Pipeline Integrity Monitoring: What’s the Present Situation for Offshore Pipelines and the Future?

2010 ◽  
Author(s):  
Brian Purvis
Keyword(s):  
Failure Modes ◽  
Present Situation ◽  
Pipeline System ◽  
Integrity Monitoring ◽  
Modes Of Failure ◽  
Industry Standards ◽  
The Future ◽  
Periodic Monitoring ◽  
Integrity Management ◽  
Critical Components

This paper will discuss both the present situation and future developments in Pipeline Integrity Monitoring. It will also highlight how integrity monitoring is a vital part of any Pipeline Integrity Management System (PIMS). To give the true picture of a pipeline’s condition, the integrity monitoring systems must identify those elements of the pipeline which are at most risk to any potential modes of failure. Pipeline integrity monitoring offshore tends to be the periodic monitoring of specified components above and below the water surface. This being in the form of long and short term monitoring programs, which are derived from threat identification, risk assessment and mitigation processes. These programs normally follow the relevant industry standards that define specific monitoring activities and frequencies, especially for the safety critical components. PIMS documentation review cycles can be long and complex, but should be undertaken on a regular basis. When these reviews are undertaken they don’t always use new data sources that could give us more information about potential failure modes. At present these processes tend to be more reactive or lagging in nature. The future monitoring of pipeline integrity should be more forward-looking and be proactive as well as being reactive. Where are the next major developments? We need to make better use of the data we have by studying trends, changes and impacts wherever possible. Also, have a better understanding of the in-service behaviour and how this can change over the life cycle of a pipeline system.

Design Criteria for Boilers and Pressure Vessels in the U.S.A.

1988 ◽  
Vol 110 (4) ◽  
pp. 430-443 ◽  
Author(s):  
Martin D. Bernstein
Keyword(s):  
Elevated Temperature ◽  
Pressure Vessel ◽  
Failure Modes ◽  
Pressure Vessels ◽  
Design Criteria ◽  
The Future ◽  
Recent Developments ◽  
Design Loads ◽  
Elevated Temperature Design

Preface. Code criteria defined. Evolution of ASME Boiler and Pressure Vessel Code. How the Code operates today. Design by rule. Evolution of design by analysis. Types of stress and their significance. Failure modes. Strength theories. Design loads. New or unusual designs. Code Cases. Interpretations. Stress limits for design by rule and design by analysis. Elevated temperature design. Recent developments. A glimpse at the future. References.

Application of Finite Element Modelling in the Qualification of Large Diameter Unbonded Flexible Risers

2002 ◽  
Author(s):  
Wenchao Zhang ◽  
Justin Tuohy
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Oil And Gas ◽  
Large Diameter ◽  
Full Scale ◽  
Flexible Pipe ◽  
Element Modelling ◽  
Norsk Hydro ◽  
Flexible Risers ◽  
Full Scale Testing

Unbonded flexible pipe has a proven track record in the offshore oil and gas industry for more than 20 years. The product is synonymous with the use of floating production systems spanning the water column and connecting subsea structures to facilitate the retrieval of hydrocarbons, provision of water injection systems and the export of processed or semi-processed fluids to main trunk pipelines or onshore. Unbonded Flexible pipe is a technically complex multi-layer structure of helically wound metallic wires and tapes and extruded thermoplastics. In 1996 Wellstream was awarded a major contract for the supply of flexible risers and flowlines as part of the Norsk Hydro Troll Olje Gas Province Development located in 350m water depth 80km west of Bergen. The development consists of two main fields, Troll East (31/3 and 31/6) and Troll West (31/2) which together have an estimated production life in excess of 50 years, making it one of the worlds largest offshore developments. Norsk Hydro is responsible for the development and operation of the production facilities. The scope of supply included 15-inch internal diameter, 213 barg design pressure, dynamic risers for the export of oil and gas from the platform to shore. At contract award, Wellstream was finalising the location of their European Manufacturing site, a facility which would have the capability of manufacturing unbonded flexible pipe with external diameters up to 24-inches. The design, manufacture and qualification of a large diameter oil and gas export riser for service in the Norwegian sector of the North Sea, considered to be one of the most severe environments in the offshore industry, provided unique challenges and attributes. These risers have now been in service for over two year, following an extensive qualification programme. This paper provides an insight into the integrated approach adopted during qualification with the successful application of finite element technology to aid full-scale testing. During a full-scale test program a finite element simulation of a 15 metre long prototype pipe was performed with special emphasis on the evaluation of contact forces between the flexible pipe and a bend limiting structure. The finite element analysis program package ANSYS is chosen for this simulation due to its special feature of contact/target elements. The paper illustrates that the use of Finite Element Modelling is indeed capable of predicting the observed behaviour of prototype risers, which are subjected to a series of dynamic load cases, in a Dynamic Test Rig (DTR). Finally, the paper concludes that focus should now be given to the advantages of using finite element tools that are verified by full scale testing to reduce development costs and schedules.

Multiscale Finite Element Analysis of Unbonded Flexible Risers

2014 ◽  
Author(s):  
Ben Edmans ◽  
Dinh Chi Pham ◽  
Zhiqian Zhang ◽  
Tianfu Guo ◽  
Sridhar Narayanaswamy ◽  
...  
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Dynamic Analysis ◽  
Large Scale ◽  
Failure Modes ◽  
Life Extension ◽  
Equivalent Material ◽  
Analysis Model ◽  
Element Analysis ◽  
Flexible Risers

Unbonded flexible risers are a key technology in existing and proposed offshore developments. With increasing water depth, the demands on risers increase and the design against hydrostatic and tension loads becomes more of a challenge. In addition, many existing subsea production systems are approaching the end of their design life and operators need to know if they can remain in-service. To enable the benefits from deepwater production and life extension projects to be realized while minimizing risks to life, property and the environment, accurate modelling and analysis tools are required to improve the prediction of failure modes and to develop a better understanding of the conditions leading to progressive failure. In this work, a multi-scale approach is adopted whereby a global dynamic analysis model is employed to determine the overall displacements of the riser and this is linked with a local model that can provide accurate forces and stresses for the prediction of collapse, fatigue damage and buckling of tensile armour wires. Firstly, we describe a nonlinear constitutive model for use in large-scale dynamic analysis of flexible risers based on an analytical homogenization of composite cylinders using the analogy between slip between pipe layers and plastic flow in continua. The model is able to reproduce the bending hysteresis behaviour observed in flexible pipes and its dependence on internal and external pressure. Secondly, we show a procedure for obtaining equivalent material parameters for this model from finite element local analyses of a flexible pipe. Finally, we show the implementation of this constitutive model in a riser system using two-dimensional co-rotational hybrid beam finite elements.

GPS Jamming and the Impact on Maritime Navigation

2009 ◽  
Vol 62 (2) ◽  
pp. 173-187 ◽  
Author(s):  
Alan Grant ◽  
Paul Williams ◽  
Nick Ward ◽  
Sally Basker
Keyword(s):  
Failure Modes ◽  
Situational Awareness ◽  
Denial Of Service ◽  
Data Gathering ◽  
Primary Source ◽  
Global Navigation Satellite Systems ◽  
Royal Institute ◽  
Gps Receiver ◽  
The Future ◽  
The Impact

Versions of this paper were first presented at the Royal Institute of Navigation GNSS Vulnerabilities and Solutions Conference held at Baska, Croatia in September 2008 and the Royal Institute of Navigation NAV 08 Conference held at Church House, Westminster, London in October 2008.The US Global Positioning System (GPS) is currently the primary source of Position, Navigation and Timing (PNT) information in maritime applications, whether stand-alone or augmented with additional systems. This situation will continue in the future with GPS, possibly together with other Global Navigation Satellite Systems (GNSS) e.g. Galileo, being the core PNT technology for e-Navigation – the future digital maritime architecture. GPS signals, measured at the surface on the Earth, are very weak. As such, the system is vulnerable to unintentional interference and jamming, resulting in possible denial of service over large geographical areas. The result of such interference could be the complete failure of the mariner's GPS receiver or, possibly worse, the presentation to the mariner of hazardously misleading information (HMI) for navigation and situational awareness, depending on how the GPS receiver reacts to the jamming incident. Recognising this, the General Lighthouse Authorities of the United Kingdom and Ireland (GLA), in collaboration with the UK Ministry of Defence (MOD) Defence Science and Technology Laboratory (DSTL), have conducted a series of sea-trials with the aim of identifying the full effects of GPS jamming on safe navigation at sea.This paper presents the key findings of these trials and provides important information on the effect of GPS denial. The GLA are playing a pivotal role in the establishment of eLoran as an independent source of PNT, taking advantage of eLoran's complementary nature, having dissimilar failure modes to GPS and the future GNSS. This paper provides information on the performance of an eLoran receiver in an area of GPS service denial. The paper presents the rationale for the work, details the system architecture employed, the data gathering efforts and finally the data analysis procedures, results and conclusions.

Stresses in Tensile Armour Layers of Unbounded Flexible Risers Loaded With External Pressure: Application to Lateral Buckling Mode

2017 ◽  
Author(s):  
Fabien Caleyron ◽  
Jean-Marc Leroy ◽  
Martin Guiton ◽  
Pascal Duchêne ◽  
Pascal Estrier ◽  
...  
Keyword(s):  
Failure Modes ◽  
External Pressure ◽  
Engineering Model ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Periodic Model ◽  
Scale Test ◽  
Flexible Risers ◽  
Offshore Field

Life6 software, developed by IFP Energies nouvelles, is the local model used by Technip to determine stresses in tensile armour layers of unbounded flexible risers. These stresses and their variations are then used to predict fatigue limits of the dynamically loaded risers. Life6 is based on periodic conditions to reduce the model length, with the assumption that all the tensile armour wires of a same layer share the same kinematics. This paper firstly presents recent improvements to obtain a better modeling of tensile armour wires kinematics, when the flexible riser loading includes external pressure. New models of the external sheath and the anti-buckling tapes have been developed and implemented in Life6. The results are successfully compared to a Finite Element periodic model. Applications to lateral buckling prediction of tensile armour layers are secondly presented in the paper. Indeed, in the design of flexible pipelines for offshore field developments, lateral buckling is one of the critical failure modes for the tensile armour wires, being associated with external pressure and flexible pipe cyclic bending. The latest developments made on the modeling of the external kernel of the flexible pipe allow to use Life6 as the basis of the enhancement of the lateral buckling engineering model used by Technip. It has been calibrated and validated against an extensive full scale test data base resulting in a physical, reliable and fast engineering model to predict lateral buckling mode. In accordance with standards, Technip methodology for flexible pipe lateral buckling determination ensures a robust and competitive design.

Carcass Failures in Multilayer PVDF Risers

2013 ◽  
Author(s):  
Knut-Aril Farnes ◽  
Claus Kristensen ◽  
Steinar Kristoffersen ◽  
Jan Muren ◽  
Nils Sødahl
Keyword(s):  
Failure Modes ◽  
Load Model ◽  
Flexible Pipes ◽  
Flexible Risers

Statoil have experienced failures in a number of flexible risers due to collapse, overload, tearing and unspiraling of the carcass in pipe structures with multi-layer PVDF pressure barrier. The paper will discuss the carcass failure modes that are characteristic for multilayer flexible pipes with particular focus on the failures due to carcass tearing. The nature of the carcass tearing problem is explained and suggestions for load model and operational policy for mitigation risk of new failures is presented.

scholarly journals Integration of future maintenance actions in the prediction parameters of the ATLAS COPCO ZR 200 compressor

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
AGNES VIRGINIE TJAHE ◽  
Blaise MTOPI FOTSO ◽  
Médard FOGUE ◽  
Noureddine Zerhouni
Keyword(s):  
Fuzzy Systems ◽  
Failure Modes ◽  
Processing Unit ◽  
Proportional Integral Derivative ◽  
Know How ◽  
Central Processing ◽  
Neuro Fuzzy ◽  
The Future ◽  
Maintenance Decision ◽  
Prediction Systems

The prediction of several failure modes of an industrial equipment requires the development of prediction systems with several interdependent parameters. The integration of future maintenance actions with this type of prediction system is a major asset for maintenance decision making. This is even more relevant in the event that after having predicted the future occurrence of several failure modes, the maintenance department does not have the necessary resources to correct all the predicted failure modes at once. In this case it becomes necessary to know how much longer the equipment will work if future partial maintenance actions that do not correct all failure modes are implemented. It is to contribute to the resolution of this problem that we propose an architecture integrating the future maintenance actions to the prediction of several interdependent parameters. This architecture is based on the association of Proportional Integral Derivative regulators to Neuro-Fuzzy systems taking into account the four previous instants to predict the next instant. An application is made with accuracies of the order of 70% for the prediction of the phenomena of fouling of the coolers and of the order of 90% for the prediction of the phenomena of clogging of the filters of the ATLAS COPCO compressor, this with Central Processing Unit values not exceeding one minute.

Increased safety and improved operation of pipelines with integrated condition sensing in flexible risers and flowlines

2014 ◽  
Vol 54 (1) ◽  
pp. 295 ◽  
Author(s):  
Bo A. Andersen
Keyword(s):  
Condition Monitoring ◽  
Failure Modes ◽  
Optimum Level ◽  
Steel Pipes ◽  
Offshore Production ◽  
Flexible Pipes ◽  
Accurate Picture ◽  
Maximum Period ◽  
Integrity Management ◽  
Flexible Risers

Continuous condition monitoring of offshore production installations is a vital part of integrity management to ensure safe operation of the asset at its optimum level for the maximum period of time. The recent implementation of fiber-optic condition monitoring embedded into the structures of flexible risers and flowlines is an important step towards turning flexible pipelines into inspectable structures. Embedded sensors enable a suite of monitoring options for both real-time response and long-term changes, which can provide a highly accurate picture of a pipeline’s condition during operation. In this paper the author reports the results from extensive full-scale testing on flexible pipes instrumented with sensors, conducted in cooperation with a major operator. The testing includes detection of a breach of the outer sheath with ingress of seawater into the annulus, remote monitoring of the location of accessories mounted on the pipe—such as buoyancy modules—monitoring of the temperature at a buried section of a pipe in the seabed, identification of hotspots, detection of breaks of tensile armor wires, and monitoring of accumulated fatigue damage in tensile armor wires during operation. Reported failure modes from flexible pipes in operation are briefly discussed to show that the major failure modes reported across all operators through the years are covered by the NOV integrated sensing systems. The detection of structural and temperature issues with integrated condition sensing in flexible pipelines will allow operators to satisfy requirements for periodic inspection, which for rigid steel pipes is performed with intelligent pigging.

Critical Assessment of PVDF Multilayer Barriers in Unbonded Flexible Risers: Applications and Benefits

2013 ◽  
Author(s):  
Upul S. Fernando ◽  
Michelle Davidson ◽  
Terry Sheldrake
Keyword(s):  
Failure Modes ◽  
Single Layer ◽  
Design Strategies ◽  
Pipe Failure ◽  
Flexible Pipe ◽  
Essential Requirement ◽  
Flexible Risers ◽  
Service Application ◽  
Test Requirements ◽  
Hydrocarbon Media

The polymer barrier is the key component in a flexible pipe structure that is specifically designed to contain hydrocarbon media within the pipe. Maintaining the integrity of the barrier for the total service life of the pipe is therefore an essential requirement to prevent any leaking or spilling of the hydrocarbon into the external environment. For high temperature (> 100°C) service PVDF is commonly used as a barrier material, and the barrier designs are based on either single layer or multilayer (two or three layers) structures depending on design strategy, manufacturing constraints and service application. This paper presents a critical review of the barrier design strategies, considering both single and multilayer structures. The main parameters in deciding a reliable barrier structure are discussed and the advantages/disadvantages of multilayers over single layers are highlighted. The different pipe failure modes/mechanisms that may be related to different barrier structures, the analyses and test requirements to evaluate and overcome these failures are discussed.

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